CyberSecBulletin
CVE-2023-23555NVD status: Modified

BIG-IP: Improper Initialization

Published Updated By the CyberSecBulletin desk

CVE-2023-23555 is a high-severity improper initialization vulnerability in BIG-IP from F5, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 15.1.8, 14.1.5.3 as the first without the flaw, so updating BIG-IP to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.64% chance of exploitation within 30 days, higher than 51% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update BIG-IP to 15.1.8 or 14.1.5.3, whichever matches your release line, or a later version.
  2. Update BIG-IP SPK to 1.6.0 or a later version.
  3. Update Big-ip Access Policy Manager to 14.1.5.3 or 15.1.8, whichever matches your release line, or a later version.
  4. Read the advisory on my.f5.com for workarounds and exact fixed builds.
  5. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
F5BIG-IP15.1.4 up to, but not including, 15.1.8; 14.1.5 up to, but not including, 14.1.5.315.1.8, 14.1.5.3
F5BIG-IP SPK1.5.0 up to, but not including, 1.6.01.6.0
F5Big-ip Access Policy Manager14.1.5 up to, but not including, 14.1.5.3; 15.1.4 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip Advanced Firewall Manager14.1.5 up to, but not including, 14.1.5.3; 15.1.0 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip Analytics14.1.5 up to, but not including, 14.1.5.3; 15.1.4 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip Application Acceleration Manager14.1.5 up to, but not including, 14.1.5.3; 15.1.4 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip Application Security Manager14.1.5 up to, but not including, 14.1.5.3; 15.1.4 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip Ddos Hybrid Defender14.1.5 up to, but not including, 14.1.5.3; 15.1.4 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip Domain Name System14.1.5 up to, but not including, 14.1.5.3; 15.1.4 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip Fraud Protection Service14.1.5 up to, but not including, 14.1.5.3; 15.1.4 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip Link Controller14.1.5 up to, but not including, 14.1.5.3; 15.1.4 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip Local Traffic Manager14.1.5 up to, but not including, 14.1.5.3; 15.1.4 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip Policy Enforcement Manager14.1.5 up to, but not including, 14.1.5.3; 15.1.4 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip SSL Orchestrator14.1.5 up to, but not including, 14.1.5.3; 15.1.4 up to, but not including, 15.1.814.1.5.3, 15.1.8
F5Big-ip Service Proxy1.5.0 up to, but not including, 1.6.01.6.0

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.5HighCNA (f5.com)
CVSS 3.17.5HighNVD

Official description

On BIG-IP Virtual Edition versions 15.1x beginning in 15.1.4 to before 15.1.8 and 14.1.x beginning in 14.1.5 to before 14.1.5.3, and BIG-IP SPK beginning in 1.5.0 to before 1.6.0, when FastL4 profile is configured on a virtual server, undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Initialization

The product does not initialize or incorrectly initializes a resource.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, in Java, if the programmer does not explicitly initialize a variable, then the code could produce a compile-time error (if the variable is local) or automatically initialize the variable to the default value for the variable's type. In Perl, if explicit initialization is not performed, then a default value of undef is assigned, which is interpreted as 0, false, or an equivalent value depending on the context in which the variable is accessed.
  • Identify all variables and data stores that receive information from external sources, and apply input validation to make sure that they are only initialized to expected values.
  • Explicitly initialize all your variables and other data stores, either during declaration or just before the first usage.

More Improper Initialization vulnerabilities (CWE-665)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in BIG-IP

All BIG-IP vulnerabilities

Recent Improper Initialization vulnerabilities

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